As a system for protecting an occupant of an automobile in case of a collision, a device for raising a front portion of a seat cushion when the vehicle collides has been proposed to prevent a submarine phenomenon in which the occupant wearing a seatbelt moves through a space below a lap belt when the vehicle collides from the front. For example, Japanese Unexamined Patent Application Publication No. 10-217818 discloses a vehicle seat having an airbag for pushing the front end portion of a seat cushion upward.
On the other hand, an air belt device (inflatable seatbelt device) is known as an occupant protection device (for example, Japanese Unexamined Patent Application Publication No. 2003-312439). In an air belt device according to this publication, both a shoulder belt and a lap belt are inflatable, and gas supplied from a gas generator provided on a buckle is injected into the inflatable shoulder belt and the lap belt through a tongue.
In addition, Japanese Unexamined Patent Application Publication No. 2002-145002 discloses an occupant protection device which protects an occupant by inflating a seat bag provided in front of a seat back, a shoulder belt, and a lap belt. According to Japanese Unexamined Patent Application Publication No. 2002-145002, the seat bag provided at the front portion of the seat, the shoulder belt, and the lap belt are inflated using a single gas generator.
In the occupant protection device according to Japanese Unexamined Patent Application Publication No. 2002-145002, the inflatable shoulder belt and the lap belt are connected to different tongues at one end thereof, and are latched to a buckle device with their respective tongues. Each of the buckle device and the tongues is provided with a gas supply path for supplying the gas from the gas generator to the shoulder belt and the lap belt.
The occupant protection devices according to Japanese Unexamined Patent Application Publication Nos. 2003-312439 and 2002-145002 must include tongues having gas supply paths, gas generators, buckle devices having gas-injecting paths for receiving gas from the gas generators, couplers for detachably coupling the gas supply paths of the tongues to the gas-injecting paths of the buckle devices, etc., and the tongue-buckle mechanisms are complex. In addition, covers for preventing foreign bodies, such as dust, from entering the gas supply paths and the gas-injecting paths when the couplers are in an unconnected state must be provided, and the structures are complex.